High-voltage power supplies have been around for many years. In one type of conventional high-voltage power supply, a multi-stage circuit topology (often referred to as a Cockroft Walton multiplier) is utilized to provide an output voltage larger than the supply voltage. The most often used construction of the Cockroft Walton multiplier includes a first string of capacitors connected laterally to a second string of capacitors through polarized sets of diodes. The orientation of the diodes determines the output polarity at the end of the string. This multiplier circuit topology is also often times described in terms of multiple stages, each comprising a pair of capacitors and a pair of diodes. Each stage may be connected to another stage to form a multi-stage multiplier circuit.
An AC voltage source or pulsing DC voltage source injected into the first string of capacitors of the multiplier circuit may cause charge to flow in each capacitor in a manner that adds voltage of each successive stage. The voltage at the end of the second string, or DC string, approaches as much as twice the input voltage times the number of stages in the multiplier. In this configuration, the components in each stage, comprising two diodes and two capacitors, may be subjected to the input voltage and not the total voltage output of the power supply. Thus, the multiplier circuit may utilize standard components with lower design limits than would otherwise be used if they were subjected to the total voltage output of the power supply.
A practical example of this conventional, Cockroft Walton power supply is depicted in FIG. 2. As shown, a 12-stage multiplier is constructed of standard electronic components, where each stage of the multiplier includes two 15 kV diodes and two 1000 pF, 15 kV capacitors. The depicted power supply assembly is approximately 9 inches long. An encapsulated transformer is energized to produce a supply voltage of approximately 8.5 kVAC. With this supply voltage, the depicted power supply may generate an output voltage of approximately 100 kV with individual components rated for 15 kV or less.
Due at least in part to the ability of the Cockroft Walton power supply to generate significant output voltages, it has been used in many applications throughout the years. However, this type of multiplier circuit is not without drawbacks. For example, depending on the application, excessive electric fields generated in the power supply may lead to ionization, power loss, flashover, and breakdown, or a combination thereof. In an effort to avoid one or more of these adverse effects, conventional Cockroft Walton power supplies, such as the one depicted in FIG. 2, may be submerged in an insulating liquid or gas. The insulating liquid or gas may prevent flashover resulting from the large electric fields generated by the power supply.
In some conventional implementations of the Cockroft Walton power supply, the multiplier components are loosely soldered together, relying on each part hanging from the other, and using loosely controlled mechanical attachment techniques. Variations in the spacing of components during fabrication or use may lead to variations in performance and possible failure. Additionally, the length and diameter of such a conventional multiplier often times is associated with a large housing.